Valve for pneumatic tools



w-llllim NOYQZG, 1929. JIM-ERSQN 1,737,312

' VALVE FOR PNEUMATIC TOOLS 7 Filed Feb. '25 1928 5' UR v 0L /K (i ,0 p 1' '0 V11? g t X g1) 7 0% 55g g1 I? 0% t A- A INVEN TOR.

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Patented Nov. 26, 1929 FRANCIS A. JIMERSON, OF ATHENS, PENNSYLVANIA, ASSIGNOR TO INGERSOLIi-RAND COMPANY, OF JERSEY CITY, NEXV'JER-SEY, A CORPORATION OF NEW JERSEY VALVE FOR PNEUMATIC TOOLS Application filed FebruaIy 23, 1928. Serial N0. 258,276.

This invention relates to pneumatic tools, but more particularly to a distributing valve for tools of that type.

One object of the invention is to control the escape of compression from the cylinder as the piston approaches the ends thereof.

Other objects will be in part obvious and in part pointed out hereinafter.

In the accompanying drawings taken in conjunction with the followin description,

Figure l is a sectional elevation of a pneu matic tool showing the valve in position to admit air into the rearward end of the cylinder, and V Figure 2 is a similar view showing the valve in its other limiting position.

Referring to the drawings, A designates a cylinder having a free exhaust port B. The cylinder is provided with a reciprocatory hammer piston C which controls the exhaust port A. closure may be provided for the front end of the cylinder by means of a bushing D which extends into the cylinder and is bored to receive slidably the shank of a working implement E. The shank of the working implement E preferably extends into the front end of the cylinder a suitable distance to prevent impact of the piston against the bushing D.

Gn the rearward end of the cylinder A is disposed a hood F which has a recess G to receive the end of the cylinder A.

The recess G is preferably of a depth to receive a valve chest designated generally by H and comprising an intermediate ring J and a pair of end plates K and L. The end plate L is interposed between the rearward end of the cylinder and the ring J and the plate K 1s seated on the rearward end of the ring J.v The parts comprising the valve chest H may be clamped in operative position by the side bolts (not shown) or other equivalent means whereby the hood F is secured to the cylin der A.

Within the ring J is formed a valve chamber O communicating at its forward end with the rearward end of the cylinder through an inlet passage P, and at its rearward end with the front end of the cylinder through an inlet passage Q extending through the parts comprising the valve chest and through the wall of thecylinder A.

Pressure fluid for actuating the piston C may be conveyed into the rearward end of the recess G through a passage R in the hood F and a portion of such pressure fluid is constantly conveyed to the rearward and front ends of the valve chamber 0 through supply passages S and T respectively.

Communication between the supply pas sages S and T and the inlet passages Q, and i is controlled by a distributing valve U disposed in the valve chamber 0. The distributing Valve preferably consists of a cylindrical block having a pair of peripheral grooves V and W which, when the valve is in its limiting positions, will register with a. passage X in the ring J. A vent Y in the hood F aii'ords constant communication between the passage X and the atmosphere.

In order to relieve the compression from the ends of the cylinder the valve Uis provided with passages Z and b. The passage Z leads from the rearward end 01 the valve to the 'roove W for conveying the compression flowing through the inlet passage Q from the front endof the cylinder to the passage X, from whence it will escape to the atmosphere through the vent Y. The passage 5 leads from the frontendof the valve to the groove V for conveying compression from the rearward end of the cylinder A. y

In the construction shown the passage S opens into an annular groove 0 which forms the rearward end of the valve chamber 0. Likewise, the passage T opens into an annular groove (Z in the plate L and adjacent the front end of the valve chamber 0. The annular grooves c and (Z are preferably of an outer diameter equal to that of the valve chamber 0. 'AS a result of this construction rearward and front portions 6 and 7" respectively of the valve which overlie these grooves form pressure areas against which pressure fluid may constantly act tending to throw the valve. The operation of the device is as follows: Pr ssure fluid entering the rearward end of therecess G flows through the passages S and T into the annular grooves c and d and acts against the pressure areas 6 and f respectively. v

In the position of the valve illustrated in Figure 1, communication between the groove 0 and the inlet passage Q, will be cut off and pressure fluid flowing through the passage T into the front end of the valve chamber 0 will pass through the inlet assage P into the rearward end of the cylind r A to impel the piston C forwardly against the working implement E. The air in the front end of the cylinder will escape through the exhaust port B until said exhaust port is covered by the piston. Thereafter such air is expolled by the piston through the inlet 'passage'Q and the passage Z in the valve into the passage X and thence through the vent Y to the atmosphere.

- During the time the valve is in the rearward position the annular groove W is in registry with the passage X. As the piston Cover-runs and uncovers the exhaust port B during the forward stroke of the piston there will be a considerable drop in pressure for- Wardly of the valve and the pressure fluid in the annular groove 0 acting against the pressure area 6 will then throw the valve to its forward position and cut ofl the supply of pressure fluid into the rearward end of the cylinder.

' Inthe forward position of the valve, pressure fluid will flow from the annular groove 0 into the inlet passage Q, thence into the front end of the cylinder to drive the piston C rearwardly'. During this stroke of the piston the air in the cylinder will be expelled through the exhaust port B until said exhaust port is covered by the piston. From this point on the air in therearward end of the cylinder will be slightly compressed and expelled through the inlet passage P and the passage b in the valve into the groove V which will then of course be in registry with the passage vX; The comprg ssion will then flow through the passage X and through the vent Y to the atmosphere, thus "completing the cycle of operations. i

As will be readily seen, due to the present invention the piston C is capable of delivering a hard blow to the working implement and the piston may travel substantially the full length of thecylinder, since, by controllin the release compression from the ends of the cylinder in the manner described such compression will not hinder the movement of the piston and cause it to shortstroke.

In case where the passages Z and b are of rather small cross sectional area as those illustrat'ed in the drawings, only a portion of the compression may flow from the ends of the cylinder at the beginning of the stroke of the hammer piston C. The compression remaining in the cylinder will then act against the ends of the valve and will assist the pressure fluid acting against the pressure areas e and f to throw the valve. However, these passages Z and Z2 may be of such area as to permit substantially all the compression to escape to the atmosphere through these channels and the pressure areas 6 and f may be of such size that the pressure fluid acting thereagainst may readily shift the valve from one position to the other.

I claim:

1. In a pneumatic tool, the combination of a cylinder and a piston, a free exhaust port in the cylinder controlled by the piston, a valve chest having a valve chamber, a vent afi'ording communication between the valve chamber and the atmosphere, inlet passages leading from the valve chamber to the cylinder, supply passages leading from a source of pressure fluid supply to the ends ofthe valve chamber, a valve in the valve chamber controlling communication between the supply passages and the inlet passages, opposed pressure areas on the valve constantly exposed to pressure fluid for throwin the valve, and crossed passages in the va ve affording communication between the inlet passages and the vent for exhausting compression from the ends of'the cylinder whenever one or the other of the crossed passages register with the vent.

2. In a pneumatic tool, the combination of a cylinder and a piston, a free exhaust port in the cylinder controlled by the piston, a valve chest on the cylinder having a valve chamber, a vent affording communication between the valve chamber and the atmosphere, inlet passages leading from the ends of the valve chamber to the ends of the cylinder, supply passages conveying pressure fluid from a source of supply to the ends of the valve chamber,.a valve in the valve chamber controlling communication between the supply passages and the inlet passages, pressure areas on the ends of the valve constantly exposed to pressure fluid for throwing the valve,'peripheral grooves in the valve, a passage in the valve and leading from the front end of the valve to the rearwardmost groove for exhausting compression from the rearward end of the cylinder when the rearwardmost groove is in registry with the vent, and another passage in the valve leading from the rearward end of the valve to the forwardmost groove for conveying compression from the front end of the cylinder to the vent during the forward stroke of the piston.

In testimony whereof I have signed this specification.

rumors. A. JIMERSON. 

